Patient-matched surgical component and methods of use

ABSTRACT

A method of automatically registering a surgical navigation system to a patient&#39;s anatomy is provided. The method comprises programming a surgical navigation system with a first spatial relationship between a surgical component and a reference array connected to the surgical component, programming the surgical navigation system with a second spatial relationship between an anatomical feature of a patient and the surgical component, installing the surgical component on the patient such that the surgical component engages the anatomical feature in the second spatial relationship, and locating the reference array with the surgical navigation system. The navigation system automatically recognizes the position of the reference array relative to the patient&#39;s anatomy.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/944,817, filed Jun. 19, 2007, the completedisclosure of which is expressly incorporated herein by this reference.

FIELD OF THE INVENTION

The present teachings relate generally to surgical navigation, and moreparticularly to patient-matched surgical components that are adapted toconform to a patient's anatomy, as well as to methods for using suchsurgical components during a surgical navigation procedure.

BACKGROUND

Surgical navigation systems, also known as computer assisted surgerysystems and image guided surgery systems, aid surgeons in locatingpatient anatomical structures, guiding surgical instruments, andimplanting medical devices with a high-degree of accuracy. Surgicalnavigation has been compared to a global positioning system that aidsvehicle operators to navigate the earth. A surgical navigation systemtypically includes a computer, a tracking system, and patient anatomicalinformation. The patient anatomical information can be obtained by usingan imaging mode such as fluoroscopy, magnetic resonance imaging (MRI),computer tomography (CT) or by simply defining the location of patientanatomy with the surgical navigation system. Surgical navigation systemscan be used for a wide variety of surgeries to improve patient outcomes.

To successfully implant a medical device, surgical navigation systemsoften employ various forms of computing technology, as well as utilizeintelligent instruments, digital touch devices, and advanced 3-Dvisualization software programs. All of these components enable surgeonsto perform a wide variety of standard and minimally invasive surgicalprocedures and techniques. Moreover, these systems allow surgeons tomore accurately plan, track and navigate the placement of instrumentsand implants relative to a patient's body, as well as conductpreoperative and intra-operative body imaging.

To accomplish the accurate planning, tracking and navigation of surgicalinstruments, tools and/or medical devices during a surgical procedureutilizing surgical navigation, surgeons often couple “tracking arrays”to the surgical components. These tracking arrays allow the surgeons totrack the physical location of these surgical components, as well as thepatient's bones during the surgery. By knowing the physical location ofthe tracking array, software associated with the tracking system canaccurately calculate the position of the tracked component relative to asurgical plan image.

It is known to use surgical navigation instruments to measure the sizeand general contour of a bone before selecting and/or manufacturing aprosthetic implant. This process allows the surgeon to choose aprosthetic component that generally resembles the shape and size of thepatient's anatomy, thereby achieving a more customized fit during theimplantation process. Despite such customization efforts, mostorthopaedic procedures still require the use of adjustable components orguides during the surgical procedure, particularly as such instrumentsare needed to fit the prosthetic components to the patient's anatomy.However, this process is time consuming, as well as subject to errorduring the placement and registration of the surgical components. Assuch, it would be desirable to improve this process to reduce surgerytime and improve prosthetic fit and/or function.

SUMMARY OF THE INVENTION

The present teachings provide a patient matched surgical component thatis custom manufactured to fit a patient's anatomy in a precise manner.To achieve such customization, the patient's anatomy is preoperativelyscanned and uploaded to a software program, which then recreates athree-dimensional model of the patient's anatomy from the scanned image.The three-dimensional model is then used by the software program toidentify and locate on the image specific known anatomical landmarks ofthe patient's anatomy. Planning software then analyzes the identifiedanatomical landmarks together with any specific surgical instructionsneeded to develop and plan a surgical protocol for the patient. Once thesurgical protocol has been approved by the surgeon, the protocol ispresented to a software program, which then uses the protocol, as wellas the preoperative scan images, to create a virtual patient matchedsurgical component. The victual component is then sent to a rapidprototyping machine or a standard machining process, which in turnmanufactures the surgical component for use during the surgicalprocedure. Because the surgical component is custom manufactured to fitthe patient's anatomy relative to specific anatomical landmarks, it canbe manufactured with a reference array positioned on its surface in apredefined spatial relationship with respect to the patient's anatomy.By having a predefined spatial relationship between the reference arrayand the patient's anatomy, the need for intra-operative registrationduring the surgical procedure is minimized or even eliminatedaltogether. Furthermore, since the patient matched component is fixableto the patient's anatomy with pins, the reference array can act as anautomatically registered rigid hone reference marker that can be usedthroughout the surgical navigation procedure.

According to one aspect of the present teachings, a method ofautomatically registering a surgical navigation system to a patient'sanatomy is provided. The method comprises programming a surgicalnavigation system with a first spatial relationship between a surgicalcomponent and a reference array connected to the surgical component,progamming the surgical navigation system with a second spatialrelationship between an anatomical feature of a patient and the surgicalcomponent, installing the surgical component on the patient such thatthe surgical component engages the anatomical feature in the secondspatial relationship, and locating the reference array with the surgicalnavigation system. The navigation system automatically recognizes theposition of the reference array relative to the patient's anatomy.

According to another exemplary embodiment herein, a method of performinga surgical procedure aided by a surgical navigation system is provided.The method comprises generating a representative model of an anatomicalfeature from an image of a patient's anatomy, using the model to make asurgical component, installing the surgical component on the anatomicalfeature by mating the surface of the component with the anatomicalfeature in the predefined spatial relationship, and tracking movement ofthe anatomical feature with a tracking system when the installedsurgical component is moved within a measurement field of the trackingsystem. According to this embodiment, the surgical component has asurface that is shaped to substantially mate with the anatomical featurein a predefined spatial relationship.

According to yet another exemplary embodiment herein, a patient matchedsurgical component is provided. The surgical component comprises a bodyhaving a surface that is shaped to substantially mate with the shape ofan anatomical feature of a patient in a predefined spatial relationship,and a reference array connected to the body, the reference array beingtrackable by a tracking system when exposed to a measurement field ofthe tracking system.

In still another exemplary embodiment, a method of performing a surgicalprocedure aided by a surgical navigation system is provided. Accordingto this exemplary embodiment, the method comprises generating arepresentative model of an anatomical feature from an image of apatient's anatomy, using the model to make a surgical component, thesurgical component having a reference array associated therewith and asurface that is shaped to substantially mate with an anatomical featurein a predefined spatial relationship, installing the surgical componenton the anatomical feature by mating the surface of the component withthe anatomical feature in the predefined spatial relationship, trackingmovement of the anatomical feature with the tracking system when theinstalled surgical component is moved within a measurement field of thetracking system, removing a portion of the anatomical feature, theremoved portion also including a portion of the installed surgicalcomponent, and tracking a remaining portion of the anatomical featurewith the tracking system, the remaining portion of the anatomicalfeature including a portion of the installed surgical component, theremaining portion of the installed surgical component including thereference array.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned aspects of the present teachings and the manner ofobtaining them will become more apparent and the invention itself willbe better understood by reference to the following description of theembodiments of the invention taken in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is a perspective view of an exemplary operating room setup in asurgical navigation embodiment in accordance with the present teachings;

FIG. 2 is a patient-matched surgical component created from apreoperative scan image of the patient's bone;

FIG. 3A is a fragmentary perspective view of a surgeon aligning thepatient-matched surgical component of FIG. 2 with a bone;

FIG. 3B is a fragmentary perspective view of the backside of thesurgical component of FIG. 3A, the component being shown aligned with abone;

FIG. 4 is a fragmentary perspective view of the patient-matched surgicalcomponent of FIG. 2 being attached to the hone by the surgeon;

FIG. 5 is a fragmentary perspective view of the patient-matched surgicalcomponent of FIG. 4 attached to the bone and its corresponding referencearray, which is connectable thereto;

FIGS. 6 and 7 are fragmentary perspective views illustrating the bone ofFIG. 5 undergoing an exemplary resection process in accordance with thepresent teachings;

FIG. 8 is a fragmentary perspective view of a surgeon aligning apatient-matched surgical component with a patient's pelvis in accordancewith the present teachings;

FIG. 9 is a fragmentary perspective view of the patient-matched surgicalcomponent of FIG. 8 being attached to the pelvis by the surgeon; and

FIG. 10 is a fragmentary perspective view of the patient-matchedsurgical component of FIG. 8 and its corresponding reference arrayconnected thereto.

Corresponding reference characters indicate corresponding partsthroughout the several views.

DETAILED DESCRIPTION

The embodiments of the present teachings described below are notintended to be exhaustive or to limit the invention to the precise formsdisclosed in the following detailed description. Rather, the embodimentsare chosen and described so that others skilled in the art mayappreciate and understand the principles and practices of the presentteachings.

FIG. 1 shows a perspective view of an operating room with surgicalnavigation system 20. Surgeon 21 is aided by surgical navigation system20 in performing knee arthroplasty, also known as knee replacementsurgery, on patient 22 shown lying on operating table 24. Surgicalnavigation system 20 has a tracking system that locates arrays andtracks them in real-time. To accomplish this, the surgical navigationsystem includes optical locator 23, which has two CCD (charge coupledevice) cameras 25 that detect the positions of the arrays in space byusing triangulation methods. The relative location of the trackedarrays, including the patient's anatomy, can then be shown on a computerdisplay (such as computer display 27 for instance) to assist the surgeonduring the surgical procedure. The arrays that are typically usedinclude probe arrays, instrument arrays, reference arrays, andcalibrator arrays. The tracking system also detects the location ofreference array 36, which is attached to patient matched surgicalcomponent 34. The relative location of patient matched surgicalcomponent 34 with respect to the patient's anatomy can then be shown oncomputer display image 38 of computer monitor 42. The operating roomalso includes instrument cart 45 having tray 44 for holding a variety ofsurgical instruments and arrays 46. Instrument cart 45 is also draped insterile cover 48 to eliminate contamination risks within the sterilefield.

The surgery is performed within a sterile field, adhering to theprinciples of asepsis by all scrubbed persons in the operating room.Patient 22, surgeon 21 and assisting clinician 50 are prepared for thesterile field through appropriate scrubbing and clothing. The sterilefield will typically extend from operating table 24 upward in theoperating room. Typically, the computer display is located outside ofthe sterile field.

A representation of the patient's anatomy 52 can be acquired with animaging system, a virtual image, a morphed image, or a combination ofimaging techniques. The imaging system can be any system capable ofproducing images that represent the patient's anatomy such as afluoroscope producing x-ray two-dimensional images, computer tomography(CT) producing a three-dimensional image, magnetic resonance imaging(MRI) producing a three-dimensional image, ultrasound imaging producinga two-dimensional image, and the like. A virtual image of the patient'sanatomy can be created by defining anatomical points with the surgicalnavigation system 20 or by applying a statistical anatomical model. Amorphed image of the patient's anatomy can be created by combining animage of the patient's anatomy with a data set, such as a virtual imageof the patient's anatomy.

The tracking system of the present invention can be any system that candetermine the three-dimensional location of devices carrying orincorporating markers that serve as tracking indicia. More particularly,the tracking system may be an active tracking system that has acollection of infrared light emitting diode (ILEDs) illuminatorssurrounding the position sensor lenses to flood a measurement field ofview with infrared light. Alternatively, the system may be a passivetracking system, which incorporates retro-reflective markers thatreflect infrared light back to the position sensor, and the systemtriangulates the real-time position (x, y, and z location) andorientation (rotation around x, y, and z axes). In yet otherembodiments, the tracking system may be a hybrid tracking system thatdetects active and active wireless markers in addition to passivemarkers. Active marker based instruments enable automatic toolidentification, program control of visible LEDs, and input via toolbuttons. Finally, in yet other exemplary embodiments, the trackingsystem may utilize electromagnetic tracking techniques. These systemslocate and track devices and produce a real-time, three-dimensionalvideo display of the surgical procedure by using electromagnetic fieldtransmitters that generate a local magnetic field around the patient'sanatomy.

The present teachings enhance surgical navigation system 20 byincorporating into the system a process for custom manufacturingpatient-matched surgical component 34 so that it fits the anatomy ofpatient 22 in a precise manner. Particularly, in addition to trackingsurgical components, the navigation system can also generatepreoperative images of the patient's anatomy and then use such images tomanufacture a surgical component that is custom matched to the patient'sanatomy. More specifically, the patient's anatomy is preoperativelyscanned and uploaded to a software program, which then recreates athree-dimensional virtual model of the patient's anatomy from thescanned image. The virtual model is then used by the software program toidentify and locate known bony anatomical landmarks or predefined pointsof the patient's anatomy. For a further description about theacquisition and registration of bony landmarks, see U.S. patentapplication Ser. No. 11/689,711, entitled “Modeling Method and Apparatusfor use in Surgical Navigation,” filed Mar. 22, 2007, which isincorporated by reference herein in its entirety.

As is appreciated by those of skill within the art, bony anatomicallandmarks are visible points or locations on a patient's anatomy, whichare identifiable by referencing known locations on the surface of thebone. For instance, known bony landmarks on the femur include, but arenot limited to, a femoral head landmark, a central knee landmark, amedial femoral condyle landmark, a lateral femoral condyle landmark, amedial epicondyle landmark, a lateral epicondyle landmark, a medialposterior condyle landmark, a lateral posterior condyle landmark and ananterior cortex point landmark. Similar bony landmarks are also found onother bones (such as the tibia, fibula, patella and pelvis, forinstance), however, for simplicity purposes, the exemplary illustrationsprovided here are specifically directed to the femur. As the presentteachings are not intended to be limiting, it should be understood andappreciated that these teachings are also applicable to bony landmarkstructures other than the femur.

Planning software analyzes the identified anatomical landmarks togetherwith any specific surgical instructions received from the surgeon anddevelops a surgical procedure or protocol for the patient. After itsapproval, the protocol is then entered into a software program, whichuses the protocol together with the preoperative scan images to create avirtual representation of a patient matched surgical component. Thevirtual representation of the surgical component is then sent to a rapidprototyping machine or a standard machining process, which in turnmanufactures a physical prototype of the surgical component. Because thesurgical component is custom manufactured to fit the patient's anatomyrelative to known anatomical landmarks, it can be manufactured toinclude a reference array that extends from its surface in a predefinedmanner. By having the reference array positioned in a predefined spatialorientation with respect to the patient's anatomy, the need to furtherregister the component intraoperatively is unnecessary; particularly asthe registration of the reference array is completed preoperativelyduring the surgical planning stages. Furthermore, since the patientmatched component can be secured to the patient's anatomy, the referencearray can also function as an automatically registered and trackablebone reference array during the surgical procedure.

The principles upon which exemplary embodiments of the present inventionrely can be understood with reference to FIG, 2, which illustratesthree-dimensional bone model 301 on surgical display image or userinterface screen 303 of monitor 305. Model 301 is based on an image ofthe patient's anatomy, which was obtained from a preoperative diagnosticimaging procedure, such as by magnetic resonance imaging (MRI), computerassisted tomography (CT), fluoroscopy, ultrasound or positron emissiontomography (PET). It should be understood that model 301 is intended toillustrate general principles of the present teachings and is notrepresentative of any particular screen shot that a surgeon may observeduring a surgical navigation procedure. Moreover, it should beunderstood and appreciated herein that processes for generatingthree-dimensional models from preoperative images of anatomical featuresare well known by those within the surgical navigation field andtherefore not discussed in detail herein.

Once three-dimensional model 301 has been created, it is then used bythe software program to identify and locate specific known anatomicallandmarks characteristic of the anatomical feature. The number ofanatomical landmarks identified on the model will depend on the bonyanatomy that is being characterized, as well as what type of surgicalprocedure is being performed on the patient undergoing the operation. Insome exemplary embodiments, however, less than about ten anatomicallandmarks are identified by the software program and represented on thethree-dimensional model. In other exemplary embodiments, less than aboutseven anatomical landmarks are identified, while in still otherexemplary embodiments, less than about three landmarks are identified.

In FIG. 2, model 301 depicts five bony anatomical landmarks common to atypical femur. These bony landmarks include the distal most point of themedial femoral condyle 307, the distal most point of the lateral femoralcondyle 309, the medial epicondyle 311, the lateral epicondyle 313 andthe anterior cortex point of the femur 315. By acquiring such bonylandmarks, the surgeon can use such information to assist in planningthe surgical protocol to be performed on the patient. For instance, byacquiring the epicondyles (311, 313), the transepicondylar axis of thefemur can be determined to assist with the rotation and positioning of afemoral implant component. Moreover, by acquiring the anterior cortexpoint of the femur 315, proper implant sizing techniques can beutilized.

Once model 301 has been created and the bony anatomical landmarksidentified, the surgeon can use the model as a visual aid and manipulateit to gather important surgical information, such as gap analysis data,resection plane details and bone alignment angles. Furthermore, if thesurgeon desires, he can rotate or manipulate model 301 so that he canvisually appreciate the general shape and characteristics of thepatient's femur, particularly as the acquired bony anatomical landmarkpoints shown on the model remain accurate as it is manipulated by thesurgeon. In addition to displaying the acquired femoral landmark points(i.e. points 307, 309, 311, 313 and 315), model 301 can also depict arepresentation of the implant component that will be implanted onto thepatient during the surgical procedure. By displaying a representation ofthe implant on the bone model, the system can gather additionalinformation useful for finalizing the surgical protocol, particularlyimplant sizing and. rotation information. The representation of theimplant can also be rotated and aligned preoperatively, particularly sothat the navigation system can calculate the location of necessary bonecuts and/or resection planes to be used during the surgical procedure.Some resection planes that can be determined preoperatively include, butare not limited to, the tibial proximal cut, the femoral distal cut, thefemoral anterior cut, as well as the chamfer cuts made by a 4-in-1resection block.

After the surgical protocol has been planned and is approved, thesoftware then creates a virtual surgical component that is custom-shapedto effect implementation of the surgical specifications (e.g., bonecuts, resection planes, drill holes, etc.) that were determined by theplanning software. In some exemplary embodiments, the surgical componentmay function as a patient-matched reference array and not include anycut slots in its body design. More particularly, in certain embodiments,the surgical component may replace one or more rigid bone referencearrays or markers typically attached to the patient's anatomy during asurgical procedure. By eliminating the use of such rigid bone referencearrays, the surgical procedure can be performed in a minimally invasivemanner, particularly as fewer incisions would be required of thepatient's anatomy. Reducing the number of required incisions during asurgical procedure is advantageous, particularly in terms of reducingassociated scarring and/or complications typically caused from suchincisions.

Once the component has been virtually designed, the virtualrepresentation is then sent to a rapid prototyping machine or a standardmachining process, which in turn manufactures a physical component thatcorresponds to the dimensional parameters of the virtual component. Forinstance, as shown in FIGS. 2, 3A and 3B, surgical component 320 hasbeen created having an interior surface 322, which matches thetopography of model 301. Surgical component 320 also includes one ormore cutting slots or guides 324, which are specifically designed toaccommodate cutting devices (e.g., saw blades) during a bone resectionprocess. It should be understood and appreciated herein that theposition, shape and directional orientation of the cutting slot(s) onthe surgical component will depend particularly on the surgicalprocedure that is to be performed on the given patient. For instance, ifthe surgeon will be performing a total knee arthroplasty, a cutting slotto accommodate the distal femur cut, such as slot 324 shown in FIG. 2,may be included. Surgical component 320 may also include one or moreholes 328 to accommodate drilling into the patient's bone and/orattaching the component to the patient's bone during a surgicalprocedure.

FIGS. 3A and 3B show surgeon 402 positioning surgical component 320relative to bone 404 during a surgical procedure. As the interiorsurface of the surgical component is shaped to substantially match thegeneral topographic landscape and contour of bone 404, the surgeon isable to align the component with the bone in such a manner that thecomponent mates with the bone in a position predefined by the software.In other words, surgeon 402 is able to press inner surface 322 ofsurgical component 320 against outer surface 406 of bone 404 until atactile sensation is felt by the surgeon indicating that the componenthas mated with or “matched” its corresponding surface of the bone.Because surgical component 320 is patient-matched to the shape of bone404, surgeon 402 can position surgical component 320 by feel with a highdegree of precision. More particularly, the body of the surgicalcomponent is shaped in such a manner that it interfits or interlocks tothe shape of the anatomical feature during installation. Thisinterfitting or interlocking relationship allows the surgeon to achievethe tactile sensation when the surgical component is correctly installedonto the anatomical feature. When the surgical component 320 is properlyor correctly installed, it sits substantially flush against the surfaceof bone 404, i.e., there will not be significant gaps around the edge ofthe component as it sits against the patient's anatomical feature orbone.

As explained above, surgical component 320 further includes one or moreholes 328 for drilling into the bone and/or for attaching the componentto the bone's surface during a surgical procedure, as well as one ormore cutting slots 324 to accommodate cutting devices during a boneresection process. According to one exemplary embodiment, holes 328 areconfigured to function as anchoring holes, which can be used forinserting temporary pins or screws into the bone to hold the surgicalcomponent into place during a surgical procedure. Holes 328 may also beconfigured into various dimensional patterns and arrangements toaccommodate the surgical plan and/or to accommodate the anatomical shapeof the bony structure or anatomical feature to which the component is tobe affixed. Moreover, in certain exemplary embodiments, the samesurgical component may be used in multiple resection procedures, wherebythe holes are arranged such that the remaining portion of surgicalcomponent 320 remains securely fastened to the bone after the initialresection is completed. Holes 328 may also be configured to usepreviously placed reference markers or anchors already attached to thesurface of the bone. More particularly, according to this embodiment,the arrangement of the holes can be positioned such that the surgeonplaces the surgical component over one or more reference markers oranchor devices previously placed into the bone. Such reference markersor anchor devices may have been placed during prior diagnostic ortherapeutic surgeries, or may have been placed preoperatively for use infuture diagnostic or therapeutic procedures.

FIG. 4 shows surgical component 320 aligned with and positionedsubstantially flush against bone 404. Once positioned, surgicalcomponent 320 can be affixed to bone 404 by inserting one or more pins502 into the bone through holes 328. Affixing surgical component 320 tobone 404 with pins, screws, or other attachment means insures that thesurgical component is securely held in place during the surgicalprocedure. In FIG. 4, surgeon 402 is shown using a pin insertion device504 to insert pin 502 into bone 404 through one of holes 328. Suchsurgical pin insertion techniques and instrumentation are known by thoseof skill within the art and therefore not discussed in detail herein.

FIG. 5 shows surgical component 320 positioned against bone 404 andsecured into place with attachment pins 502. Surgical component 320 alsoincludes a quick connect receptacle 602, which is configured to connectto a tracking device, such as a reference array. According to thisembodiment, tracking or reference array 604 is provided with a quickconnect base 606 that dimensionally corresponds with receptacle 602 suchthat a removable snap-fit connection can be achieved between the twocomponents. While FIG. 5 illustrates a snap-fit attachment means betweenthe reference array and the component, it should be understood that inother embodiments, reference array 604 may be “pre-installed” ontosurgical component 320, whereby no additional attachment means isrequired after the component is attached to the bone. It should also beunderstood and appreciated that any attachment means known within theart may be used to secure reference array 604 to surgical component 320.Such attachment means include, but are not limited to, welding, fusing,molding, gluing, threading, snap-connections, quick disconnectconnections and the like.

Once reference array 604 is attached to surgical component 320,navigation system 20 is able to locate and track its position inreal-time and display its tracked position on a surgical plan image. Inother words, once the navigation system locates the array, the systemautomatically knows its position with respect to the landmarksidentified on the model image, as well as where it has beenpre-registered with respect to the image. To accomplish this, and withreference to FIG. 6, cameras 702 of optical locator 704 detect in spacethe position of markers 706, which extend from the surface of referencearray 604. It should be understood and appreciated herein that whilethis embodiment shows four markers 706 attached to the frame ofreference array 604, in other embodiments less than four markers may beused, while in yet other embodiments, more than four markers may beused. For instance, in some embodiments using electromagnetic trackingtechnology, only one marker is needed to track the position of thesurgical component in space. In yet other embodiments, three markers maybe used to triangulate the position of the surgical component in space.As such, it should be fully appreciated that the present teachings arenot intended to be limited herein.

To detect the position of the markers in space, known triangulationmethods arc used. These triangulation methods allow the navigationsystem to determine the relative location of the reference array and itsmarkers with respect to the patient's anatomy, and then display the sameon a surgical plan image. As reference array 604 is trackable inreal-time, the position of bone 404 can also be tracked in real-time,particularly since reference array 604 is fixably attached to itssurface by way of surgical component 320. As explained above, by havingreference array 604 positioned relative to the surgical component 320 ina predefined spatial manner, the need for intra-operative registrationduring the surgical procedure is substantially minimized.

As used herein, “predefined” refers to a preoperatively planned spatialrelationship between the surgical component and the anatomical featureof the patient to which the component is to be attached. In other words,once the component is installed onto the anatomical feature in itspredefined spatial orientation, it is automatically registered with thesystem and can be tracked by the navigation system for the remainder ofthe procedure without further registration techniques. Moreover, sincethe patient matched component is fixably secured to the patient'sanatomy throughout the surgical procedure, reference array 604 is ableto function as a rigid reference bone marker to track bone 404 duringthe surgical procedure. Such rigid bone reference arrays are commonlyused in orthopaedic surgical procedures and are able to track apatient's bones with respect to various surgical instruments during asurgical navigation procedure. Because the presently disclosed referencearrays are preoperatively registered with the navigation system in apredefined manner with respect to the patient's anatomy, thesecomponents can be used to track the patient's anatomy without the needto insert additional rigid array markers into the patient during theprocedure. Moreover, because such surgical components are registeredwith the navigation system during the preoperative planning steps of thesurgical procedure, timely intraoperative registration processes arealso unnecessary.

An exemplary illustration of a bone undergoing a resection process inaccordance with the present teachings is depicted in FIGS. 6-7. Surgicalinstrument 714 may optionally include a marker array 715, which can befurther identified and tracked by cameras 702 of optical locator 704.However, since surgical component 320 was custom designed to match andmate with the specific shape of bone 404, the surgeon does not need totrack the position of the surgical instrument relative to the boneduring the surgical procedure. More particularly, the position ofcutting slot 324 on surgical component 320 was previously registeredwith the tracking system during the preoperative planning stages of thesurgical procedure. As such, once the surgeon attaches the component tothe bone in its predetermined position, he can proceed directly toresecting the bone with the surgical instrument without further trackingor registering of the surgical instrument. As such, it should beunderstood that the depiction of marker array 715 on surgical instrument714 is optional and is not intended to limit the scope of the presentteachings.

Referring still to FIGS. 6 and 7, as surgeon 716 moves instrument 714relative to bone 404, the tracking system locates and tracks markerarray 715 in real-time. The relative location of marker array 715 isthen shown on surgical plan image 708 of computer display 710. Thetracking system detects the location of surgical instrument 714 relativeto bone 404 by referencing the position of marker array 715 as it moveswith respect to reference array 604, which is fixably attached to bone404 by way of surgical component 320. The position of saw blade 712 ofsurgical instrument 714 is displayed on surgical plan image 708 as cutplane 713. By viewing cut plane 713 on surgical plan image 708, surgeon716 can confirm that the surgical component is positioned properly,although as just noted, this step is optional since the component can beproperly positioned by the surgeon by feel alone.

FIG. 7 shows a portion of bone 404 removed after surgeon 716 hasinserted saw blade 712 into cut slot 324 of surgical component 320. Aportion of the surgical component 321 remains affixed to the removedbone by attachment pin 329. Because reference array 604 is stillattached to bone 404 by way of surgical component 320, the surgicalnavigation system continues to recognize and track the position of bone404 and the remaining portion of the attached surgical component 320 inreal-time throughout the remainder of the surgical procedure. As such,the remaining portion of surgical component 320, and its reference array604, can be used for additional steps in the surgical procedure, such asthe removal or modification of a second predefined part of the boneafter the initial resection, or the placement and use of additionalsurgical components. The tracked remaining portion of surgical component320 can also be used to perform other surgical procedures that requiretracking, such as ligament balancing, range of motion and impingementanalyses.

It should be understood and appreciated herein that while FIG. 7 depictsportion 321 of surgical component 320 being removed with saw blade 712,in other exemplary embodiments, portion 321 may be removed by beingsnapped, broken or cleaved away from surgical component 320. Forinstance, cut slot 324 could be replaced by a groove or cleave that isdesigned to be physically broken or torn away from the surgicalcomponent after it has been attached to the patient's anatomy. As such,the attachment means useful for the present teachings are not intendedto be limited herein.

While the above-described embodiments illustrate the presently disclosedsurgical components as being useful for knee related applications, itshould be appreciated and understood herein that the exemplarycomponents disclosed herein may also be used together with any otheranatomical features without straying from the present teachings. Forinstance, in certain exemplary embodiments, the surgical components mayalso be used together with hip-related navigation applications. Moreparticularly, as is known within the surgical navigation field,registration processes for the hip can be quite challenging,particularly as the surgeon must register both sides of the patient'spelvis, including rolling the patient onto their side to collect datapoints and then re-draping and re-scrubbing the patient between suchregistration steps. By using the presently disclosed surgicalcomponents, navigating the hip during a surgical procedure issignificantly simplified, particularly as the need to register the hipintraoperatively is eliminated.

Further principles upon which exemplary embodiments of the presentinvention rely can be understood with reference to FIG. 8. FIG. 8depicts surgical component 802, which has been created by a rapidprototyping machine or a standard machining process to match thedimensional parameters of a virtual representation of a patient's pelvisaccording to the process described above. More particularly, surgicalcomponent 802 has an interior surface that matches the topographiclandscape of pelvis 803. According to this embodiment, surgeon 806positions surgical component 802 relative to pelvis 803 during a hipprocedure. As the interior surface of the surgical component is shapedto substantially match the general topographic landscape and contour ofpelvis 803, the surgeon is able to align the component with the pelvisin such a manner that the component mates with the pelvis in a positionpredefined by the software. In other words, surgeon 806 is able to pressthe inner surface of surgical component 802 against outer surface 804 ofpelvis 803 until a tactile sensation is felt by the surgeon indicatingthat the component has mated with or “matched” its corresponding surfaceof the pelvis. Because surgical component 802 is patient-matched to theshape of pelvis 803, surgeon 806 can position surgical component 802 byfeel with a high degree of precision. When properly positioned, surgicalcomponent 802 will sit substantially flush against the surface of pelvis803, i.e., there will not be significant gaps around the edge of thecomponent as it sits against the patient's pelvic bone.

Surgical component 802 also includes one or more holes 808 for drillinginto the pelvis and/or for attaching the component to the pelvis'ssurface during a hip procedure. According to one exemplary embodiment,holes 808 are configured to function as anchoring holes, which can beused for inserting temporary pins or screws into the pelvis, therebyholding the surgical component into place during a surgical procedure.For instance, FIG. 9 shows surgical component 802 aligned with andpositioned substantially flush against pelvis 803. Once positioned,surgical component 802 can be affixed to pelvis 803 by inserting one ormore pins 810 into the pelvis through holes 808. Affixing surgicalcomponent 802 to pelvis 803 with pins, screws, or other attachment meansinsures that the surgical component is securely held in place during thesurgical procedure. In FIG. 9, surgeon 806 is shown using a pininsertion device 812 to insert pin 810 into pelvis 803 through one ofholes 808.

FIG. 10 shows surgical component 802 positioned against pelvis 803 andsecured into place with attachment pins 810. Surgical component 802 alsoincludes a quick connect receptacle 814, which is configured to connectto a tracking device, such as reference array 816. Once reference array816 is attached to surgical component 802, navigation system 20 is ableto locate and track its position in real-time and display its trackedposition on a surgical plan image. In other words, once the navigationsystem locates the array, the system automatically knows its positionwith respect to the landmarks identified on the model image, as well aswhere it has been pre-registered with respect to the image. Toaccomplish this, cameras 818 of optical locator 820 detect in space theposition of markers 817, which extend from the surface of referencearray 816. To detect the position of the markers in space, knowntriangulation methods are used. These triangulation methods allow thenavigation system to determine the relative location of the referencearray and its markers with respect to the patient's anatomy, and thendisplay the same on a surgical plan image. As reference array 816 istrackable in real-time, the position of pelvis 803 can also be trackedin real-time, particularly since reference array 816 is fixably attachedto its surface by way of surgical component 802. As explained above, byhaving reference array 816 positioned relative to the surgical component802 in a predefined spatial manner, the need for intra-operativeregistration during the surgical procedure is substantially minimized.

In additional to navigating knees and hips, the present teachings canalso be used with surgical procedures involving the shoulder, spine,ankle, elbow, skull or any other type of bony structure found within thehuman anatomy. As such, the present teachings are not intended to belimited herein.

While an exemplary embodiment incorporating the principles of thepresent invention has been disclosed hereinabove, the present inventionis not limited to the disclosed embodiments. Instead, this applicationis intended to cover any variations, uses, or adaptations of theinvention using its general principles. Further, this application isintended to cover such departures from the present disclosure as comewithin known or customary practice in the art to which this inventionpertains and which fall within the limits of the appended claims.

1.-9. (canceled)
 10. A computer-readable medium including instructionsthat, when executed by a computing device, cause the computing device toperform operations comprising: generating a representative model of ananatomical feature from an image of a patient's anatomy; using the modelto select a virtual surgical component; installing the virtual surgicalcomponent on the representative model of the anatomical feature bymating a surface of the virtual surgical component with the anatomicalfeature in a predefined spatial relationship; tracking movement of asurgical cutting instrument with a tracking system; tracking movement ofthe anatomical feature with the tracking system when the surgicalcutting instrument is moved within a measurement field of the trackingsystem; displaying the representative model and a representation of thesurgical cutting instrument on a display of the surgical navigationsystem; and displaying a cutting plane of the surgical cuttinginstrument relative to the anatomical feature in the representativemodel.
 11. (canceled)
 12. The computer-readable medium of claim 10,wherein tracking movement of the anatomical feature with the trackingsystem comprises tracking movement of a reference array attached to thesurgical cutting instrument.
 13. The computer-readable medium of claim10, wherein the instructions further comprise identifying a finitenumber of predefined points on the anatomical feature, the predefinedpoints being shown on the model to assist in cutting the anatomicalfeature.
 14. The computer-readable medium of claim 13, wherein at leastone of the predefined points is a bony anatomical landmark selected fromat least one of a femoral head landmark, a central knee landmark, amedial femoral condyle landmark, a lateral femoral condyle landmark, amedial epicondyle landmark, a lateral epicondyle landmark, a medialposterior condyle landmark, a lateral posterior condyle landmark and ananterior cortex point landmark. 15.-20. (canceled)
 21. Thecomputer-readable medium of claim 10, wherein the instructions furthercomprise: generating a surgical plan from the representative model andthe virtual surgical component; and wherein displaying therepresentation of the surgical cutting instrument on the display toverify a cutting plane of the surgical cutting instrument relative tothe anatomical feature includes displaying a cut plane of the surgicalplan on the representative model on the display.
 22. Thecomputer-readable medium of claim 21, wherein displaying therepresentative model and the representation of the surgical cuttinginstrument includes displaying a cutting blade of the surgical cuttinginstrument in the cutting plane on the representative model in thedisplay relative to the cut plane.
 23. A system for conducting navigatedknee arthroplasty on a patient, the system comprising: a controller; acomputer-readable storage medium including instructions that, whenexecuted by the controller, cause the controller to perform operationscomprising: acquiring a representation of a knee joint of the patient;creating a three-dimensional virtual model of the knee joint of thepatient from the representation; identifying bony landmarks on a femurwithin the three-dimensional virtual model of the knee joint; developinga surgical protocol for the patient including anatomic orientationinformation of the femur from an analysis of the bony landmarks;tracking with an optical locator a retro-reflective marker array affixedto a surgical cutting instrument; and displaying a current cut plane ofthe surgical cutting instrument on a surgical display during surgery inreference to a planned cut plane from the surgical protocol, wherein thesurgical display is located outside of a sterile field in which thesurgical cutting instrument is located, the current cut plane comprisinga cutting path of the surgical cutting instrument determined from thesurgical plan.
 24. The system of claim 23, wherein the instructionsfurther comprise using a surgical navigation system to calculate a bonecut in the current cut plane at least in part by analyzing thepredefined points on the three-dimensional virtual model.
 25. The systemof claim 23, wherein developing the surgical protocol comprises:displaying a rotatable and manipulable visual representation of thethree-dimensional virtual model of the knee joint of the patient on atleast one display; and displaying a rotatable and resizablerepresentation of a femoral knee implant on the visual representation ofthe three-dimensional virtual model on the at least one display.
 26. Thesystem of claim 23, wherein displaying the current cut plane includes:displaying the three-dimensional virtual model on the surgical display;and displaying the current cut plane on the three-dimensional virtualmodel displayed on the surgical display, the current cut plane includinga representation of a saw blade of the surgical cutting instrument onthe surgical display, the surgical cutting instrument comprising ahandheld surgical saw.
 27. The system of claim 26, wherein theinstructions further comprise confirming positioning of the surgicalcutting instrument by viewing the representation of the saw bladerelative to the displayed current cut plane.
 28. The system of claim 23,wherein the instructions further comprise: creating a virtualrepresentation of a patient-matched surgical component; manufacturingthe patient-matched surgical component; and affixing the patient-matchedsurgical component to the knee of the patient.
 29. The system of claim28, wherein displaying the current cut plane includes displaying thepatient-matched surgical component on the surgical display.
 30. Thesystem of claim 29, wherein the instructions further comprise: trackingwith an optical locator a retro-reflective marker array affixed to thepatient-matched surgical component attached to the patient in thesterile field.
 31. The system of claim 30, wherein the instructionsfurther comprise: pre-registering a first spatial relationship betweenthe patient-matched surgical component and the retro-reflective markerarray connected to the surgical cutting instrument; and pre-registeringa second spatial relationship between an anatomical feature of the kneejoint of the patient and the patient-matched surgical component.
 32. Thesystem of claim 29, wherein the patient-matched surgical componentcomprises a cutting guide.
 33. A computer-readable medium for use inperforming a surgical procedure aided by a surgical navigation system,the computer-readable medium including instructions that, when executedby a controller, cause the controller to perform operations comprising:generating a representative model of an anatomical feature from an imageof anatomy of a patient; creating a virtual representation of apatient-matched surgical component based on the representative model;displaying the virtual representation on the representative model;manipulating the representative model of the anatomical feature and thevirtual representation of the patient-matched surgical component togather surgical information using a computer-operated planning program;planning a surgical protocol from the gathered surgical information, thesurgical protocol including a cutting plane disposed relative to theanatomical feature; displaying a surgical plan image from the surgicalprotocol and the patient-matched surgical component on a computerdisplay, the surgical plan image including a representation of thecutting plane relative to the anatomical feature; tracking a resectionplane of a surgical instrument on the computer display while displayingthe patient-matched surgical component and the representative model; andguiding the surgical procedure on the bone by displaying at least aportion of the resection plane of the surgical instrument relative tothe cutting plane of the surgical protocol on the representative model.34. The computer-readable medium of claim 33, wherein thepatient-matched surgical component comprises a prosthetic implantdevice.
 35. The computer-readable medium of claim 34, furthercomprising: creating a virtual representation of a patient-matchedsurgical instrument based on the representative model.
 36. Thecomputer-readable medium of claim 35, further comprising: tracking thepatient-matched surgical instrument; and displaying the patient-matchedsurgical instrument in the computer display.
 37. The computer-readablemedium of claim 35, wherein the patient-matched surgical instrumentcomprises a guide.
 38. The computer-readable medium of claim 33, whereinthe surgical instrument comprises a drill.